Week 5 Blood & Blood Vessels Flashcards
What is blood?
Specialised connective tissue where the ground substance is fluid.
What are the constituents of blood?
Plasma (Plasma proteins & other solutes) Formed elements (Red blood cells, White blood cells, & Platelets)
There are 3 formed elements. What are their names & main functions?
1) Red blood cells (erythrocytes) - Oxygen transport.
2) White blood cells (Leucocytes) - Part of the immune system.
3) Platelets (Thrombocytes) - Involved in clotting.
Describe erythrocytes?
Disc shaped blood cell with no nuclei, mitochondria or ribosomes, that contain haemoglobin.
What are the different types of white blood cells?
Neutrophils, eosinophils & basophils - The granulocytes.
Monocytes & lymphocytes - The agranulocytes.
What are the functions of blood?
It is invloved in homeostsis through -
1) The transportation of gases, nutrients, organic & inorganic substances.
2) The regulation of volume & chemicals.
3) Protection via the WBC’s & plasma proteins.
What is haemostasis?
The prevention of blood loss.
What are the 3 phases of haemostasis?
1) Vascular phase,
2) Platelet phase,
3) Coagulation phase.
Descirbe the 3 steps within the vascular phase of haemostasis?
Step one - The cut triggers vasoconstriction. This causes the endothelial cells to contract & expose the basal lamina.
Step two - The endothelial cells release chemicals & hormones which stimulate further smooth muscle contraction of the blood vessel. Cell division of the endothelial cells also begins as part of the repair process.
Step 3 - The endothelial cells become sticky which may seal of the blood flow but it means that other substances will stick to it.
What are the 2 parts to the platelet phase of haemostasis called & what occurs during their processes?
Platelet adhesion - platelets stick to the sticky endothelial surface & exposed basal laminae. As the platelts stick down they change shape, increase in size, &release substances.
Platelet aggregation - with the release of these chemicals the platelets become sticky & stick together to form a platelet plug which may be sufficient enough to close small breaks.
What are the 3 parts to the coagulation phase of haemostais?
1) Extrinsic pathway,
2) Intrinsic pathway,
3) Common pathway.
What is the difference between the intrinsic & extrinsic pathways of the coagulation phase of haemostasis?
The extrinsic pathway is followed when the damge has occured as a reulst of external forces e.g. kick, stab etc. Whereas the instrinic pathway occurs when damage to the blood vessel occurs as a reslt of internal damage e.g. increased cholesterol, calcium plaques etc.
What is Haemophillia?
It is a clotting disorder where there is a genetic fault with factor 8 which can lead to uncontrollable bleeding.
Arteries & veins have 3 common layers, what are they?
1) Tunica Intima (interna),
2) Tunica Media,
3) Tunica Externa.
Put the following vessels in order of size?
Veins, arterioles, venules, capillaries, arteries, .
Arteries-Arterioles-Capillaries-Venules-Veins
big - small - big
What processes are in place to ensure venous return occurs?
1) Veins have valves in them to prevent back flow of blood.
2) Muscles pumps e.g. gastrocnemius.
3) Respiratory pump.
What is hypertension & name the 2 types that exist?
Blood pressure greater than 140/90mmHg.
Essential & Secondary hypertension.
What is atherosclerosis?
The hardening of an artery due to the deposition of an atherosclerotic plaque
Name 4 pathologies of the venous system?
1) Deep vein thrombosis (DVT),
2) Varicose veins,
3) Venous insufficiency,
4) Venous ulcers.
What happens to the cardiovascular system with age?
Cardiovascular capabilities decline with age. The blood has a decreased amount of haematocrit & the blood vessels are more likely to suffer from pathology e.g. atherosclerosis, aneurysms, varicose veins & venous insufficiency.
